diff --git a/server-spi-private/src/main/java/org/keycloak/events/Errors.java b/server-spi-private/src/main/java/org/keycloak/events/Errors.java
index 807434a9ed..429be9143c 100755
--- a/server-spi-private/src/main/java/org/keycloak/events/Errors.java
+++ b/server-spi-private/src/main/java/org/keycloak/events/Errors.java
@@ -30,6 +30,7 @@ public interface Errors {
     String CLIENT_DISABLED = "client_disabled";
     String INVALID_CLIENT_CREDENTIALS = "invalid_client_credentials";
     String INVALID_CLIENT = "invalid_client";
+    String UNAUTHORIZED_CLIENT ="unauthorized_client";
     String CONSENT_DENIED = "consent_denied";
     String RESOLVE_REQUIRED_ACTIONS = "resolve_required_actions";
 
diff --git a/services/src/main/java/org/keycloak/protocol/oidc/grants/device/endpoints/DeviceEndpoint.java b/services/src/main/java/org/keycloak/protocol/oidc/grants/device/endpoints/DeviceEndpoint.java
index 6bb4630d69..6e08031256 100644
--- a/services/src/main/java/org/keycloak/protocol/oidc/grants/device/endpoints/DeviceEndpoint.java
+++ b/services/src/main/java/org/keycloak/protocol/oidc/grants/device/endpoints/DeviceEndpoint.java
@@ -364,8 +364,7 @@ public class DeviceEndpoint extends AuthorizationEndpointBase implements RealmRe
 
         if (client == null) {
             event.error(Errors.INVALID_REQUEST);
-            throw new ErrorPageException(session, null, Response.Status.BAD_REQUEST, Messages.MISSING_PARAMETER,
-                OIDCLoginProtocol.CLIENT_ID_PARAM);
+            throw new ErrorResponseException(Errors.INVALID_REQUEST, "Missing parameters:"+ OIDCLoginProtocol.CLIENT_ID_PARAM,Response.Status.BAD_REQUEST);
         }
 
         checkClient(client.getClientId());
@@ -376,8 +375,7 @@ public class DeviceEndpoint extends AuthorizationEndpointBase implements RealmRe
     private ClientModel checkClient(String clientId) {
         if (clientId == null) {
             event.error(Errors.INVALID_REQUEST);
-            throw new ErrorPageException(session, null, Response.Status.BAD_REQUEST,
-                Messages.MISSING_PARAMETER, OIDCLoginProtocol.CLIENT_ID_PARAM);
+            throw new ErrorResponseException(Errors.INVALID_REQUEST, "Missing parameters:"+ OIDCLoginProtocol.CLIENT_ID_PARAM, Response.Status.BAD_REQUEST);
         }
 
         event.client(clientId);
@@ -385,24 +383,22 @@ public class DeviceEndpoint extends AuthorizationEndpointBase implements RealmRe
         ClientModel client = realm.getClientByClientId(clientId);
         if (client == null) {
             event.error(Errors.CLIENT_NOT_FOUND);
-            throw new ErrorPageException(session, null, Response.Status.BAD_REQUEST,
-                Messages.CLIENT_NOT_FOUND);
+            throw new ErrorResponseException(Errors.INVALID_CLIENT, "Client not found.", Response.Status.BAD_REQUEST);
         }
 
         if (!client.isEnabled()) {
             event.error(Errors.CLIENT_DISABLED);
-            throw new ErrorPageException(session, null, Response.Status.BAD_REQUEST, Messages.CLIENT_DISABLED);
+            throw new ErrorResponseException(Errors.INVALID_CLIENT, "Client disabled.", Response.Status.BAD_REQUEST);
         }
 
         if (!realm.getOAuth2DeviceConfig().isOAuth2DeviceAuthorizationGrantEnabled(client)) {
             event.error(Errors.NOT_ALLOWED);
-            throw new ErrorPageException(session, null, Response.Status.BAD_REQUEST,
-                Messages.OAUTH2_DEVICE_AUTHORIZATION_GRANT_DISABLED);
+            throw new ErrorResponseException(Errors.UNAUTHORIZED_CLIENT, "Client is not allowed to initiate OAuth 2.0 Device Authorization Grant. The flow is disabled for the client.", Response.Status.BAD_REQUEST);
         }
 
         if (client.isBearerOnly()) {
             event.error(Errors.NOT_ALLOWED);
-            throw new ErrorPageException(session, null, Response.Status.FORBIDDEN, Messages.BEARER_ONLY);
+            throw new ErrorResponseException(Errors.UNAUTHORIZED_CLIENT, "Bearer-only applications are not allowed to initiate browser login.", Response.Status.FORBIDDEN);
         }
 
         String protocol = client.getProtocol();
@@ -413,7 +409,7 @@ public class DeviceEndpoint extends AuthorizationEndpointBase implements RealmRe
         }
         if (!protocol.equals(OIDCLoginProtocol.LOGIN_PROTOCOL)) {
             event.error(Errors.INVALID_CLIENT);
-            throw new ErrorPageException(session, null, Response.Status.BAD_REQUEST, "Wrong client protocol.");
+            throw new ErrorResponseException(Errors.UNAUTHORIZED_CLIENT, "Wrong client protocol." , Response.Status.BAD_REQUEST);
         }
 
         session.getContext().setClient(client);
diff --git a/testsuite/integration-arquillian/tests/base/src/test/java/org/keycloak/testsuite/oauth/OAuth2DeviceAuthorizationGrantTest.java b/testsuite/integration-arquillian/tests/base/src/test/java/org/keycloak/testsuite/oauth/OAuth2DeviceAuthorizationGrantTest.java
index fa945d2461..7e9185c475 100644
--- a/testsuite/integration-arquillian/tests/base/src/test/java/org/keycloak/testsuite/oauth/OAuth2DeviceAuthorizationGrantTest.java
+++ b/testsuite/integration-arquillian/tests/base/src/test/java/org/keycloak/testsuite/oauth/OAuth2DeviceAuthorizationGrantTest.java
@@ -28,6 +28,7 @@ import org.junit.Test;
 import org.keycloak.OAuth2Constants;
 import org.keycloak.admin.client.resource.ClientResource;
 import org.keycloak.admin.client.resource.RealmResource;
+import org.keycloak.events.Errors;
 import org.keycloak.models.ClientScopeModel;
 import org.keycloak.models.OAuth2DeviceConfig;
 import org.keycloak.models.utils.KeycloakModelUtils;
@@ -851,6 +852,51 @@ public class OAuth2DeviceAuthorizationGrantTest extends AbstractKeycloakTest {
         verificationPage.assertInvalidUserCodePage();
     }
 
+    @Test
+    public void testNotFoundClient() throws Exception {
+        oauth.realm(REALM_NAME);
+        oauth.clientId("test-device-public2");
+        OAuthClient.DeviceAuthorizationResponse response = oauth.doDeviceAuthorizationRequest("test-device-public2", null);
+
+        Assert.assertEquals(400, response.getStatusCode());
+        Assert.assertEquals(Errors.INVALID_CLIENT, response.getError());
+        Assert.assertEquals("Invalid client credentials", response.getErrorDescription());
+    }
+    @Test
+    public void testClientWithErrors() throws Exception {
+        try {
+            ClientResource client = ApiUtil.findClientByClientId(adminClient.realm(REALM_NAME), DEVICE_APP_PUBLIC);
+            ClientRepresentation clientRepresentation = client.toRepresentation();
+            clientRepresentation.getAttributes().put(OAuth2DeviceConfig.OAUTH2_DEVICE_AUTHORIZATION_GRANT_ENABLED, "false");
+            client.update(clientRepresentation);
+            oauth.realm(REALM_NAME);
+            oauth.clientId(DEVICE_APP_PUBLIC);
+
+            //DeviceAuthorizationGrant not enabled
+            OAuthClient.DeviceAuthorizationResponse response = oauth.doDeviceAuthorizationRequest(DEVICE_APP_PUBLIC, null);
+            Assert.assertEquals(400, response.getStatusCode());
+            Assert.assertEquals(Errors.UNAUTHORIZED_CLIENT, response.getError());
+            Assert.assertEquals("Client is not allowed to initiate OAuth 2.0 Device Authorization Grant. The flow is disabled for the client.", response.getErrorDescription());
+
+            clientRepresentation.getAttributes().put(OAuth2DeviceConfig.OAUTH2_DEVICE_AUTHORIZATION_GRANT_ENABLED, "true");
+            clientRepresentation.setBearerOnly(true);
+            client.update(clientRepresentation);
+
+            //BearerOnly client
+            response = oauth.doDeviceAuthorizationRequest(DEVICE_APP_PUBLIC, null);
+            Assert.assertEquals(403, response.getStatusCode());
+            Assert.assertEquals(Errors.UNAUTHORIZED_CLIENT, response.getError());
+            Assert.assertEquals("Bearer-only applications are not allowed to initiate browser login.", response.getErrorDescription());
+
+        } finally {
+            ClientResource client = ApiUtil.findClientByClientId(adminClient.realm(REALM_NAME), DEVICE_APP_PUBLIC);
+            ClientRepresentation clientRepresentation = client.toRepresentation();
+            clientRepresentation.getAttributes().put(OAuth2DeviceConfig.OAUTH2_DEVICE_AUTHORIZATION_GRANT_ENABLED, "true");
+            clientRepresentation.setBearerOnly(false);
+            client.update(clientRepresentation);
+        }
+    }
+
     private void openVerificationPage(String verificationUri) {
         driver.navigate().to(verificationUri);
     }